Directional control valve

ABSTRACT

A directional control valve has a supply pressure chamber in communication with a source of pressurized air and a vent pressure chamber in communication with the surrounding environment. Three ducts in respective communication with three ports, each interconnect the supply pressure chamber and the vent pressure chamber. Two rotors, each including two arcuate cuts, are fixedly secured to a rotatable shaft which extends between the chambers. Positioned within the ends of the ducts are springloaded carbon seals which are adapted to sealingly engage the inboard faces of the rotors. The cuts in the rotors are arranged so that the ports are pressurized and vented in a predetermined sequence as the shaft is rotated.

United States Patent 137/596, 137/625.24 ..F16k 11/02, Fl6k 11/10 ABSTRACT: A directional control valve has a supply pressure chamber in communication with a source of pressurized air and a vent pressure chamber in communication with the surrounding environment. Three ducts in respective communication with three ports, each interconnect the supply pressure chamber and the vent pressure chamber. Two rotors, each including two arcuate cuts, are fixedly secured to a rotatable shaft which extends between the chambers. Positioned within the ends of the ducts are spring-loaded carbon seals which are adapted to sealingly engage the inboard faces of the rotors. The cuts in the rotors are arranged so that the ports are pressurized and vented in a predetermined sequence as the shaft is rotated.

v DIRECTIONAL CONTROL VALVE BACKGROUND OF THE INVENTION This invention relates generally to directional control valves and more particularly to directional control valves which incorporate a plurality of control ports. Even more particularly the invention relates to directional control valves which employ a sequencing feature to direct pressure signals to various control ports thereof.

In certain aircraft the thrust reversers are pneumatically controlled by means of a plurality of pressure signals which must be sequentially applied as a function of throttle position. If a directional control valve is mechanically connected to the aircraft throttles, it is highly desirable that this valve require a minimum operating force so that throttle movement is not significantly hindered.'A valve selected forsuch an application should also exhibit other advantageous qualities such as being able to perfonn effectively when subjected to temperature transients and having a low weight and volume.

SUMMARY OF THE INVENTION The invention provides a pneumatically balanced directional control valve which is capable of producing a pressure signal at a control port thereof in response to a small input force. A valve according to the invention affords a low friction, light weight, and small volume design.

A housing has a vent chamber and a pressure chamber which respectively communicate with the ends of at least one duct, which in turn communicates with a signal port. A rotor assembly has drivingly interconnected rotors, each of which has at least one arcuate cut therein. The rotors seal off the respective ends of the duct from the chambers until the cuts respectively place the chambers in communication with the duct. The cuts are disposed in each rotor such that respective states of communication between the pressure chamber and the duct and between the vent chamber and the duct are at least partially mutually exclusive. Thus, in one rotor position the port receives a high-pressure signal from the pressure chamber and in another position the port receives a low-pressure signal from the vent chamber. A valve according to the invention may be designed to yield a plurality of pressure signals by providing additional ducts and corresponding cuts in the rotors. The arrangement of the cuts with respect to the ducts is determinative of the sequencing of the pressure signals as the rotors are rotated. The arcuate cuts are machined so as to wipe across the port seals at a variable radius to clean and wear the carbon seal faces uniformly.

The supply pressure rotor and the vent pressure rotor are located in the housing in such a manner as to be substantially pressure balanced in the axial direction. This feature minimizes the torque required to rotate the rotor assembly.

All seals in the valve of the invention are of the spring-.

loaded type and hence the valve sealing is insensitive to differential thermal expansions. In addition to providing satisfactory sealing throughout a broad temperature spectrum, these seals permit a liberal axial tolerancing and therefore contribute to a reduced manufacturing cost.

It is a primary object of the invention to provide a directional control valve having rotors to control the pressure signals generated thereby.

Accordingly, it is an object of the invention to provide a rtary directional control valve in which the rotor thereof is substantially pressure balanced so as to require a low operating torque.

It is another object to provide a directional valve having a performance which is unaffected by temperature transients.

It is a further object to provide a directional valve which has a low weight and occupies a small volume.

. For further objects and advantages of this invention reference should be made to the following detailed description .and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a front elevational view of a directional control valve according to the invention.

FIG. 2 is a rear elevational view of the directional control valve of FIG. I.

FIG. 3 is a sectional view of the directional control valve of FIG. 1 taken along the line 33.

' FIGS. 4a and 4b are front elevational views of the vent pressure rotor and the supply pressure motor respectively taken along the lines 4A-4A and 48-48 of FIG. 3.

FIG. 5 is a schematic diagram of a fluid system incorporatinga directional control valve according to the invention. FIG. 6 is a chart illustrating the pressure sequencing of the valve of FIGS. 1-48.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT Turning now to the drawings and more particularly to FIG.

I, there is shown a front view of a directional control valve of ,the invention. A housing, generally indicated at 10, comprises pfront portion, generally indicated at 12, which includes three axial mounting projections 14, I5, and 18 and an upper portion 20 supported by vertical legs 22 and 24. Housing 10 is also formed by a rear portion generally indicated at 26 in FIGS. 2 and 3. The front and rear portions 12 and 26 of housing 10 are secured together by a lightweight band clamp 28. The housing portions are precision investment castings from precipitation-hardened stainless steel. This material exhibits superior high temperature strength, corrosion resistant, and antigalling qualities.

Rear portion 26 of housing 10 has three axial ducts 30, 32 and 34 passing therethrough which respectively communicate with blocker port 36, retract port 38, and extend port 40 by means of conduits 42, 44, and 46, which are shown by dashed lines in FIG. I. A supply pressure port 48 (FIG. 2) communicates with an inlet passage 50 which directly communicates with a pressure chamber 52 defined by the intervening space between front and rear portions 12 and 26. Axial ducts 30, 32, and 34 also communicate with pressure chamber 52 as shown in FIG. 3. End stamping 54 is fastened to the end of rear portion 26 by cap screws 56 to define a vent pressure chamber 58. End stamping 54 includes a plurality of circumferentially disposed apertures 60 adjacent the rearextremity thereof and an vantireaction cap 62. Thus, an outlet passage is formed by apertures 60 and end stamping 54.

Mountedfor rotation within axially aligned central passages in the portions of housing 10 is a rotor shaft 64 as shown in FIGS. I and 3. Ball bearings 66 disposed in rear portion 26 surrounds shaft 64. A bearing loading spacer 68 biased by a spring wave 70 urges separator bearing 72 toward rear chamber 58. A supply pressure rotor 74 is fixedly mounted upon shaft 64 for rotation therewith, supply pressure rotor 74 being disposed in supply pressure chamber 52. A vent pressure rotor 76 is also fixedly mounted upon shaft 64 for rotation therewith, rotor 76 being disposed in vent pressure chamber 58. The vent pressure rotor is secured to shaft 64 by a self-locking nut 78 which bears against spacer washer-80 which in turn abuts rotor 76.

Duct 30 has spring-loaded carbon-faced seals 82 and 84 axially positioned at the inlet (front) and outlet (rear) ends respectively which contact the respective rotors 74 and 76. Similarly, ducts 32 and 34 have similar seals positioned at their ends which contact the rotors in a like manner. These seals, which sealingly engage the rotors, are employed to prevent flows in the ducts except as permitted by the positioning of the rotors as is explained hereinafter.

Surrounding the input shaft 64 and located in annular cavities in housing 10 are two axial spring-loaded carbon-faced shaft seals 86 and 88 which function to isolate high-pressure supply air in chamber 52 from the bearings and the shaft. As is evident from FIG. 3, the carbon faces of these seals are in sliding contact with the respective lateral faces of rotor 74. Rotor 74 is pressure-balanced since these seals are at a common radius. The shaft seals 86 and 88 are of the same construction as the seals in the ducts, but are of a larger size.

The carbon face seals comprise a cylindrical metal housing and a pressure-balanced, circular face-type sealing member made of carbon, which is spring loaded to contact the adjacent sealing surface and compensate for wear thereon. This type of seal is capable of withstanding temperatures up to 550F. and preventing leakage of any consequence at differential pressures up to 700 p.s.i. The valve sealing provided by these seals is not subject to deterioration of ditTe rentia expansions within the valve since all seals are of spring-loaded variety and hence remain in intimate sealing engagement during such expansions. Even slight scuffing" of the rotors at the ends of the ducts is not detrimental since the carbon seals contact only a limited circumferential area of the rotorsv In addition to the improvement in overall sealing provided by the carbon seals, their limited freedom of axial travel relative to their respective housings permits more liberal axial tolerances within the valve which may be attended by significant cost reductions.

Turning now to FIGS. 4A and 48 wherein the construction of the rotors is shown, rotor 74 is provided with two arcuate cuts 90 and 92 and a central opening 94 having a keyway 96 which is adapted to slide over a mating indexing key (not shown) on shaft 64. Similarly rotor 76 is provided with arcuate cuts 100 and 102 and a central opening 104 having a keyway 106 adapted to also slide over the key on shaft 64. The accuracy of the valve timing or sequencing is assured by the illustrated construction. The indexing key on the rotor shaft is accurately located relative to the female input index spline 108 (FIG. I) and the keyways 96 and 106 in the respective rotors 74 and 76 are accurately located relative to the respective porting cuts 90, 92 and 100, 102. This arrangement promotes accurate repeatability and interchangeability in the assembly and contributes to a reduction in tolerance buildups among the parts thereof. The rotors are shown at the 55 idle index position as they would appear looking along the lines 4A-4A and 48-48.

As the rotors 76 and 74 rotate in unison from their respective FIG. 4A and FIG. 43 positions in the clockwise direction (shown by the solid arrows) their angular position increases above 55, and conversely, as the rotors 76 and 74 rotate in unison from their respective FIG. 4A and FIG. 48 positions in the counterclockwise direction (shown by the phantom arrows), their angular position decreases. The fixed locations of the inlet areas of the ducts 30, 32, and 34 adjacent rotor 74 are shown outlined in FIG. 48 by dashed lines. Similarly, the fixed locations of the outlet areas of the ducts 30, 32, and 34 adjacent rotor 76 are shown outlined in FIG. 4A by dashed lines. The inlet and outlet areas are, of course, defined by the inner peripheries of the carbon faces of the carbon-faced seals. Thus, FIGS. 4A and 4B show the orientation of the rotors when the shaft occupies its 55 idle index position. Since the rotors are fixedly mounted upon shaft 64, they both rotate through the same angular displacement and in the same direction as shaft 64.

As will be noted from FIGS. 4A and 4B, the axes of the arcuate cuts are referenced to respective centers different from those of the respective rotors. This geometrical configuration permits the cuts to simultaneously slide and wipe across the seals positioned in the ends of the ducts, thereby distributing wear uniformly over the respective seal faces and providing cleaning action thereon. This sliding and wiping results in an extension of seal operating life. It will, of course, be understood that if desired the cuts may be made in the peripheries of the respective rotors.

The rotors are adapted to be rotatably positioned over the ducts to place the chambers in communication therewith ac cording to a predetennined sequencing. The sequencing arrangement enables states of communication between the supply pressure chamber and a particular duct, and the vent pressure chamber and that duct to be at least partially mutually exclusive.

Referring to FIG. 5 an application for a valve according to the invention is illustrated. On this application the valve controls the position of a piston (not shown) in a cylinder 110, it being understood that the piston is operatively connected to the thrust reversers (load) on a gas turbine engine. A supply flow of air is directed into a conduit which bifurcates into respective segments which communicate with the directional control valve 10 and a blocker valve 1 12 which remains closed until a high-pressure signal is communicated thereto from blocker port 36. The extend port 40 and the retract port 38 respectively communicate with the outboard ends of a spooltype four-way valve 114 which in turn communicates'with cylinder 110. Therefore, after blocker valve 112 is opened by a pressure signal from blocker port 36, valve 114 is positioned in accordance with pressure signals from ports 38 and 40, to control the position of the piston and hence thrust reversers. It is contemplated, in such a system, that shaft 64 would be operatively connected to the pilots throttles so as to be responsive movements thereof.

In order to more fully appreciate the operation of the valve in such a system, reference should be had to FIG. 6 wherein the sequencing of the valve of FIGS. l4B is illustrated. The horizontal axis of the chart represents the angular position of the rotors. It should be initially noted that as the throttles are retarded from a forward thrust position to a reverse thrust position, the angular displacement of the rotors progressively decreases. At angular displacements in excess of 61, the blocker and extended ports 40 and 38 communicate with the vent chamber 58 via respective cuts and 102 in vent pressure rotor 76. In this position, vent flow from duct 32 and its communicating retract port 38 is prevented by sealing contact with rotor 76, and duct 32 communicates with pressure chamber 52 via cut 90 in rotor 74, and hence, retract port 38 is pressurized. At angular displacements less than 59 the blocker port is pressurized thereby arming the thrust reverser system. At angles less than 475 extend port 40 is pressurized via cut 92 in supply pressure rotor 74. In this position retract port 38 is vented via cut 102 in rotor 76.

Between 61 and 59 the blocker port 36 is neither vented nor pressurized as duct 30 is sealed at both ends by the respective rotors. Thus, with respect to the blocker port 30, states of fluid communication with the supply pressure chamber 52 and the vent pressure chamber 58 are totally mutually exclusive (overlapped).

Between 49.5 and 475 the extend port 40 and retract 38 each fluidly communicate with both of the pressure chambers by means of their associated ducts and respective cuts 102, 92 and 102, 90. Within this range of angular displacement, flow passes from the supply pressure chamber to the vent pressure chamber through ducts 32 and 34. It should be apparent, that with respect to the extend port 40, respective states of communication with the vent pressure chamber and the supply pressure chamber are only partially mutually exclusive (underlapped). The same is, of course, true of the retract port 38.

Therefore, assuming that the throttles are lifted over the reverse detent and positioned such that the angular position of the rotors is less than 475, the retract port 38 is vented and the extend port 40 is pressurized, thus allowing air to flow through the open (pressurized) blocker valve 112 to the left port of cylinder via valve 114. The flow from the right port of cylinder 110 is simultaneously vented via valve 1 14.

It will be understood that modifications and variations may be effected without departing from the spirit and scope of the novel concepts of the present invention, such as positioning the rotors in locations remote from the chambers or replacing shaft 64 with a gear drive assembly. It will also be understood that a valve according to the invention could provide pressure signals for any number of ports.

I claim:

1. A directional control valve comprising:

a housing having a port, a duct communicating with said port, an inlet passage, an outlet passage, a supply pressure chamber and a vent pressure chamber, said inlet passage .5 v p p 6 communicating with said supply pressure chamber and 2. A valve asdefiried in .claim I, further including:

said outlet passage communicating with said venting prestwo spring-loaded seals respectively mounted at said inlet sure chamber, and said duct fluidly interconnecting said and outlet ends of said duct in respective sealing contact PP)! Pressure Chamber am Said Vent P'F Chamber; with said supply pressure rotor and said vent pressure roa rotatably mounted supply pressure rotor m the housing in ton sealing engagement end of 52nd f 3. A valve as defined in claim 2, wherein said seals comsupply pressure rotor having an arcuate cut thereln Prise;

aqapted P be row'ably Posmoned to carbon faces spring urged into sealing contact with said roplace said supply pressure chamber in communication tors.

with said port; and 10 a rotatably mounted vent pressure rotor drivingly interconnected to said supply pressure rotor in sealing engagement with anoutlet end of said duct, said vent pressure rotor havin an arcuate cut therein ada ted to be rotatably po sitioned over said outlet end t: place said a rfnmatlle shaft mqumed m a centralPasSage m Sald hous' vent pressure chamber in communication with said port 2 a z gg r l f such that respective states of communicationbetween Va ve as e me m 6 3 w e axes o Sal said Supply pressure chamber and Said pom and between cuts are referenced to respective centers different from those said vent pressure chamber and said port are at least parof the respective romrs' tially mutually exclusive.

4. A valve as defined in claim I, further including:

two seals respectively positioned on the sides of said supply pressure rotor in sealing engagement therewith.

5. A valve as defined in claim 1, further including: 

1. A directional control valve comprising: a housing having a port, a duct communicating with said port, an inlet passage, an outlet passage, a supply pressure chamber and a vent pressure chamber, said inlet passage communicating with said supply pressure chamber and said outlet passage communicating with said venting pressure chamber, and said duct fluidly interconnecting said supply pressure chamber and said vent pressure chamber; a rotatably mounted supply pressure rotor in the housing in sealing engagement with an inlet end of said duct, said supply pressure rotor having an arcuate cut therein adapted to be rotatably positioned over said inlet end to place said supply pressure chamber in communication with said port; and a rotatably mounted vent pressure rotor drivingly interconnected to said supply pressure rotor in sealing engagement with an outlet end of said duct, said vent pressure rotor having an arcuate cut therein adapted to be rotatably positioned over said outlet end to place said vent pressure chamber in communication with said port such that respective states of communication between said supply pressure chamber and said port, and between said vent pressure chamber and said port are at least partially mutually exclusive.
 2. A valve as defined in claim 1, further including: two spring-loaded seals respectively mounted at said inlet and outlet ends of said duct in respective sealing contact with said supply pressure rotor and said vent pressure rotor.
 3. A valve as defined in claim 2, wherein said seals comprise: carbon faces spring urged into sealing contact with said rotors.
 4. A valve as defined in claim 1, further including: two seals respectively positioned on the sides of said supply pressure rotor in sealing engagement therewith.
 5. A valve as defined in claim 1, further including: a rotatable shaft mounted in a central passage in said housing, said rotors being mounted on said shaft.
 6. A valve as defined in claim 1, wherein the axes of said cuts are referenced to respective centers different from those of the respective rotors. 